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Hydrogen peroxide reacting with potato to produce oxygen and water.

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Introduction

Hydrogen peroxide reacting with potato to produce oxygen and water Planning experimental procedure: An enzyme is a biological protein which speeds up or catalyses chemical reactions in living things. They can allow the reaction to occur when it would not have done so otherwise, for example at a lower temperature. I am going to find out if the enzyme in potato catalyses the reaction where hydrogen peroxide (H[2]O[2]) breaks down to water (H[2]O) and oxygen (O[2]). In order to find out more about the reactions I will change one of the variables and measure the outcome. The variables are the amount of enzyme, as shown by the surface area of potato and the amount of hydrogen peroxide, as shown by its concentration in solution. The easiest outcome to measure is the amount of oxygen (O[2]) produce. Another outcome is the amount of water (H[2]O) produced, but this is a smaller volume as it is a liquid (while oxygen is a gas) and it is harder to measure accurately. I will use a constant surface area of potato as it is difficult to measure and vary accurately enough to get good results. ...read more.

Middle

Strength of hydrogen peroxide (%) Volume of Oxygen collected Test no. 1 ( cm^3) Volume of Oxygen collected Test no.2 ( cm^3) Volume of Oxygen collected Test no.3 ( cm^3) Volume of Oxygen collected Test no.4 ( cm^3) Volume of Oxygen collected Average ( cm^3) 20 7^ (5) 6 6.1 6.367 15 6.1 (4) 5.2 5.3 5.53 10 3.5^ 3.5 4.1 3.7 5 0.5^ 0.4 1.2 0.7 0 0^ 0 0 0 [ ] Table 1 For 20% and 15% concentrations of hydrogen peroxide the anomaly was test number two. I have already explained why I have not done an extra test for 5% concentrations and for 10% and 0% the results of the tests are similar. Analysing evidence and drawing conclusions. I have found that my hypothesis is true, `more oxygen will be produced at higher concentrations of hydrogen peroxide'. I have demonstrated this in graphical form in graph 1, where I have plotted concentration of hydrogen peroxide solution against volume of oxygen produced. As can be seen from the line of best fit (red), there is a steady gradient with progressively more oxygen produced as the concentration of hydrogen peroxide rises. ...read more.

Conclusion

10 readings). 3. Because it seems that the graph may not follow a straight line, a more accurate picture might appear if readings were taken for more different concentrations of hydrogen peroxide (e.g. at 1% intervals). 4. Because the graph seems to flatten out at the highest concentration of hydrogen peroxide (20%), I could have got a better idea of the reaction if I had taken readings at higher concentrations (e.g. 25%, 30%). 5. The results could also have been made more accurate if I ha more time to carry out the experiment. Because of time pressure my partner and I hurried with the experiment, and the measurements of the size of the potato and the volume of hydrogen peroxide where sometimes hurried. They were not as accurate as they would have been if we had more time. 6. The measurement of the volume of oxygen produced could have been more accurate. This could have been achieved with a taller, thinner measuring cylinder so that the vertical distance between the volume markers was greater. It would also have been easier to measure accurately if the measuring cylinder was made of clear glass instead of plastic. ...read more.

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